Antigenic relationships among viruses of the tick-borne encephalitis complex as studied by monoclonal antibodies

Tick-borne encephalitis (TBE) monoclonal antibodies showed haemagglutination-inhibiting (HI) activity against viruses belonging to the TBE complex except of Powassan virus. The HI titre with Kyasanur forest disease virus was lower than with tick-borne encephalitis virus, when monoclonal antibodies were incubated with the antigen at +4 degrees C for 30 min. Langat virus could be distinguished from other viruses of the TBE complex when the antigen was incubated with monoclonal antibodies at +4 degrees C for 18 hr. A close antigenic relationship was demonstrated between tick-borne encephalitis, louping-ill, Negishi and Omsk haemorrhagic fever viruses.